1. Field of the Invention
The present invention relates to a method for measuring surface roughness of a lubricant applied to a photoreceptor drum, and an image forming apparatus employing the measurement results.
2. Description of Related Art
In an electrographic image forming apparatus, a toner image is formed on the surface of a photoreceptor. The toner image is transferred from the surface of the photoreceptor onto a transfer target such as an intermediate transfer belt. Moreover, the image forming apparatus includes a cleaning blade to remove toner remaining on the surface of the photoreceptor after transfer.
Furthermore, to reduce abrasion or suchlike of the photoreceptor, an application brush and a solid lubricant (referred to below as a lubricant) are provided immediately downstream from the cleaning blade in the rotational direction of the photoreceptor. The application brush is disposed so as to be able to contact the surface of the photoreceptor. Moreover, the lubricant is pressed against the application brush by a biasing unit. With this configuration, the lubricant is scraped by rotating the application brush, and thereafter, the scraped lubricant is supplied to the surface of the photoreceptor. As a result, a lubricant film is formed on the surface of the photoreceptor (see, for example, Japanese Patent Laid-Open Publication Nos. 2007-139808 and 2008-224828).
Incidentally, the surface of the photoreceptor coated with the lubricant film is subjected to charging and exposing steps so that an electrostatic latent image is formed thereon. Thereafter, a developing device rotates a developing roller provided therein, which is in contact with the surface of the photoreceptor. As a result, a developer is supplied to the surface of the photoreceptor, so that a toner image is formed. At this time, the lubricant on the surface of the photoreceptor might be scraped in part and incorporated into the developer contained in the developing device. In particular, lubricant particles remaining without becoming films adhere to the surface of the lubricant film, and the adhesion of these lubricant particles to the surface of the lubricant film is so weak that they are separated from the surface of the photoreceptor merely by contacting the supplied developer. Therefore, the lubricant particles are readily incorporated into the developer in the developing device through contact with the developer or the developing roller.
Such lubricant incorporation results in a reduced amount of charge in the developer. As a result, the image forming apparatus is susceptible to powder smoke generated therein, hence occurrence of an uneven image density, i.e., reduced image quality.